To determine whether the air toxics
included in USEPA’s National-Scale Air
Toxics Assessment (NATA) could be a potential human
health problem in New Jersey, NJDEP compares the estimated NATA
air concentrations to their chemical-specific health
benchmarks. We divided the modeled air
concentration by the health benchmark
to get a number we call a risk ratio. If the risk ratio
for a specific chemical is greater than one, it may be of concern. The risk ratio also shows
just how much higher or lower the estimated air concentration
is than the health benchmark. For more information,
see How We Estimate Risk
from Air Toxics. For "Air Toxics of Concern" (see below), results of NJDEP's risk assessment are presented in two ways: State Risk Maps, and County Risk Ratio Tables.

New Jersey’s methods for estimating risk using
the NATA results are somewhat different from USEPA’s
methods, and therefore risk results presented here
are different from the risk estimates found on the
USEPA's NATA web site. New Jersey compares health benchmarks to the modeled ambient concentrations, while USEPA converts the ambient data into "exposure concentrations" using an exposure model that incorporates numerous assumptions about the demographics and activity patterns within a census tract. Resulting exposure concentrations may either be higher or lower than ambient concentrations. Dispersion models have been tested over time by comparisons with ambient monitoring data, and have generally been shown to be comparable within a factor of two. However, for exposure modeling we feel that at this stage of development it adds a level of complexity and uncertainty that confuses rather than clarifies the true levels of exposure.

AIR TOXICS OF GREATEST CONCERN IN NEW JERSEY FOR 2002

Of the 181 air toxics that USEPA included in the 2002 NATA, about one-third do not have toxicity values, or corresponding health benchmarks. For those that do, our analysis of the state and county average air toxics concentrations indicates that 21
of the pollutants are "of concern" because they were predicted to exceed their
health benchmarks in one or more counties.
20 of these are cancer-causing (carcinogenic) chemicals,
and one (acrolein) is evaluated as a non carcinogen. Predicted
concentrations of these pollutants vary around the
state, depending on the type of sources that emit
them. This is summarized in the table below. For
more information on source types click on point,
area, and mobile sources, and background
concentrations. For more information on which areas are impacted by these chemicals of concern, see the chemical-specific maps below.

2002 CHEMICALS OF CONCERN
IN NEW JERSEY

Pollutant

Number/Name
of Counties
Above Health Benchmarks

Primary
Emissions
Source

Acetaldehyde

21

Mobile, background

Acrolein

21

Mobile

Arsenic
Compounds

19

Background, area

Benzene

21

Mobile, Background

1,3-Butadiene

21

Mobile,
background

Cadmium
Compounds

1 (Warren)

Major

Carbon
Tetrachloride

21

Background

Chloroform

21

Area,
background

Chromium VI

19

Major, Background

1,4-Dichlorobenzene

8

Area, Background

1,3-Dichloropropene

1 (Hudson)

Area

Diesel
Particulate Matter

21

Mobile

Ethylbenzene

7

Mobile

Ethylene Oxide

7

Area, Background

Formaldehyde

21

Mobile,
background

Methyl Chloride

21

Background

Methyl tert-Butyl Ether

21

Background

Naphthalene

19

Area

PAH/POM

18

Area

Perchloroethylene

7

Area,
background

1,1,2-Trichloroethane

1 (Salem)

Area

* For more information on which areas are impacted
by the chemicals of concern, see the chemical-specific
maps below.

MAPS
SHOWING THE DISTRIBUTION OF THE 2002 AIR TOXICS
OF CONCERN IN NEW JERSEY

To
see a state map showing the spatial variation in
modeled air concentrations (at the census-tract level) for one of the twenty-one
chemicals of concern, click on the chemical name:

To
see a statewide or county -specific table containing
the 2002 NATA-based risk results (including ambient air concentrations, health
benchmarks, risk ratios, and source category contributions)
for each of the 21 air toxics of concern, click on
the state name or county names below.

The symbol ug/m3 is micrograms per cubic
meter, the amount (in micrograms) of a chemical in
a cubic meter of air. This is also known as a concentration.

PAH/POM is "polycyclic aromatic hydrocarbons/polycyclic organic matter." It is made up of many different compounds, which are not all reported individually to the NEI. In order to model and assess risks from all the individual compounds that make up this category, EPA broke PAH/POM compounds into 8 groupings and assumptions were used to determine a health benchmark for each group. The concentrations and risk associated with the groupings were then added together for each census tract. The health benchmark displayed in these tables is an average across all the census tracts in New Jersey.

Previous NATA Risk Results

USEPA has completed three National-Scale Air Toxics Assessments, every third year beginning with 1996. Before that, they conducted a "Cumulative Exposure Project" (CEP) for 1990 which also included an assessment of air toxics. However, they emphasize that the methods used to conduct emissions inventories, modeling, and risk assessment vary somewhat from year to year, so the results are not exactly comparable.